Sound amplifier



July 12, 1927. F. D. ARNOLD scum) AMPLIFIER Filedduly 26, 1922 d y m la. 4

2 Sheets-Sheet 1 Inf/enter: flanivflv 1,635,303 July 12,1927. F'QARNOLD SOUND AMPLIFIER Filed July 26, 1922 2 Shuts-Shae!- Z Patented July 12, 1927.

F Fl C E FRANK n. ARNO D, or nU MBoLn'r, Iowa 7 vsourm AMP IFIER.

Application filed July 28, 1922. Belial No. 577,531.

This" invention relates to; sound amplifiers, and morespecifically'to ame aphone attachment in the form, roughly, 0 a harp or stringed instrument, the same to be used in connection'not only with musical instruments, but also in connection with radio and telephone loud speakers and the like. x

Amongthe objects of this invention are to providea resonator of .such form and con- 1 structionthat it can be: fitted into a megaphone in such manner that the sound waves must pass therethrough when passing through the mega hone; to provide an instrument of this 0 aracter, which when applied in the megaphone oramplifier of a phonograph, not only amplifies or increases the volume of sound, by its sympathetic vibration, butalso' Inellows or softens and enriches the tone to'produce a sound amplifier which may be used with phonographs, graphophones, radio and telephone loud speakers, and thelike, to increase the volume ofsound and improvethe quality of tone; to provide an improved form of instrument capable of being installed in existing. amplifiers without modification J thereof to provide inana paratus. of the character described means or adjusting the tension ofthe sound amplifiers so that tones of various pitches may be amplified ;land such further objects, advantages, and capabilities as will hereinafter more. fully appear. I I

My invention further resides in. the combination,' construction and arrangement of parts illustrated in the accompanying drawlugs, and While I have shown therein preferred; embodiments, I desire the sameto be understood as illustrative only and not as limiting my invention. a M I In the accompanyingdrawings, Fig. '1 is an elevation of what I now consider the preferred formv of my invention.

Fig. 2 is an elevation of a modificationof the construction shown in Fig. 1'.

Fig. 3 is a' longitudinal section substantially alongthe plane indicated by the line 3-3 Fig.1, the intermediate cross bars belng omitted. g

Fig.4 is a vertical central section throu h a me aphone or amplifier showing a mo ilied orm of my device applied thereto. F ig; 5. is an .elevationof the attachment shown in Fig. 4 detached from the megahone or amplifier, thetsame being viewed in the directionof the arrow in: Fig.4.

2 Fig. 6, is an enlarged. sectional view substantially along the plane indicated by the line 6-6 of Fig. 5.

Referring more in detail to these drawings, the subject matter of. my invention is shown as comprising a frame having adjustably mounted thereon filamentous vibratory resonators. The frame comprises side members 1 and 2, and top and bottom members 3 and 4, cross members 5, 6 and 7 and braces 8 and 9.

shown in Fig. 2 the brace member 9 is omitted, because not necessary with the. short bottom member 4. 'It will of course be obvious that, if desired, the legs 10 may be omitted, though it is at present considered preferable to use the same. On the frame described above are stretched filamentous vibratory resonators 11 and 12, extending vertically and transversely of the frame, respectively. These resonators may I11 the construction I be formed from variousmaterials, but it is at present considered preferable to use metallic members in the form. of wire. In the preferred form of my invention these wires each have one end secured to a base. plug 13 and the opposite end secured to a tuning plug 14.

In the simplest embodiment of this construction the frame will be provided with but one series of-these wires, but it has been foundpreferable to use two or more sets of strings as shown in Figs. 1 and 3. It is, of course, obvious that these vibrating members must 'beso mounted that no two will-be in loose contact, since if they are'in such con tact, there will be present'an undesirable rattling. In a large megaphone l have used a plurality of such devices as shown in Figs. 1 and 2, and have gotten very good results, while in smaller megaphones it' has been found desirable to mount these variouslayers of vibratory members on a single frame as shown. in Fig. 3.

In order to accomplish the sep'aration of the different layersv of wires, as outlined above, resort may be had to various means but I have chosen to show the same as accomplished-with frets 15. Various mechanical equivalents of the frets 15 shown in Fig. 3 will suggest themselves to one skilled in the art. These may consist, for example,

of ridges formed on the bars 3 and 4 or land. 2, or one pair of opposite bars may be made thicker than the other pair.

What is now considered a less desirable method of mounting the vibratory members,

is shown in Figs. 4t, 5 and (3, in which member 1 is shown as provided with notches 16 and member 2 with tensioning plugs 14: extending entirely through the same. WVires 12, or the like, are doubled and have their doubled portions extending through the notches 16 and each one has its opposite ends secured to the tensioning plugs let so that turning of the plugs will cause tensioning of both portions of the wires 1 The difficulty with this method of stringing is that it is harder to secure unison of pitch between the two arms of a string 12 than it is to secure unison of pitch between two separate strings, tensioned independently as in Figs. 1, 2 and 3. lVith this type of construction it will be possible, though not as convenient, to pass vibratory members both ways across the frame, and it would be obvious to one skilled in the art that means should be provided for keeping the vibrating members out of contact with the cross pieces 5, 6 and 7. This may be accomplished by means of frets similar to mounted on members 3 and 4, by having members 5, 6 and 7 thinner than members 3 and l, or in any other desired manner. It is also clear that if the extra set of wires is used in this form it will be necessary, as in the preceding form, to have the adjaeei'it wires on one side of the frame separated from each other, so that there may be no contact during vibration.

lVhile the tensioning pins 14 are shown in Figs. 1 and 5 as having their angular shaped ends extending forwardly toward the free end of the megaphone M so that the same be engaged by means of a tightening wrench, it is not necessary that they be so mounted, since it is ordinarily preferable to remove the amplifier from the megaphone for adjusting the tension of the vibrators.

While the frames illustrated are more es pecially adapted for megaphones which are rectangular in cross section, it is clear that they are not necessarily limited in their use to megaphones having such form, nor is it necessary that the amplifiers should have straight sides, it being feasible to have one or more of the bars 1, 2 and 3 curved in form so as to more nearly extend completely across the opening through the megaphone.

'While I have shown no particular means of securing the frame within the megaphone, it will be understood that any suitable means may be employed, said means preferably be ing suchas will secure more or less intimate contact between the frame and megaphone so that vibrations of the latter will be t'ansmitted to the former and from that to the filamentous vibratory members. It is understood of course that, from the shape of the frame shown in Fig. 1, it is primarily adapted to be placed in the megaphone at a rightangle to the axis thereof, whether the megaphone be a rectangular box or a tapered box such as shown in Fi 4 and Whether the box be of circular or rectangular cross section. It is also understood that, while the frame is shown herein as constructed of wood, the same may be also made of metal, if so desired.

It is of course understood that the specific description of structure set forth above may be departed from without departing from the spirit of my invention as set forth in this specification and the appended claims.

Having now described my invention, 1 claim l. The combination with a megaphone or tone amplifier having entrance and exit openings at its ends, and a resonator including a frame and filamentous resonating elements extending thereacross, said frame be ing located within said megaphone or amplifier transversely to the path of sound waves passing from end to end thereof, and the filaments extending transversely of the length of the amplifier.

2. A resonator for a sound amplifier c0lnprising a frame having opposite side members, pins mounted in a side member, and filamentous resonating elements extending across the frame and being connected to the opposite ends of said pins, each pin being adjustable to adjust the tone pitch of said filamentous resonating element, said elements extending t 'ansversely of the length of the frame.

3.-An attachment for a sound amplifier comprising a frame provided at one side with positioning means for filamentous vibratory resonators, tensioning members at the opposite side of said frame, and filamentous resonators mounted upon said frame and each having its ends secured to a single tensioning means on opposite sides of said positioning means and an intermediate portion passing over a corresponding positloning means.

t. A resonator for a sound amplifier comprising a frame, holding means on opposite sides and faces thereof, filamentous resonating means passing across opposite faces of said frame and being held in place by said holding means, said holding means includ ing means for adjusting each resonating means to adjust the tone pitch of said resonating means.

5. A sound device, comprising a sound amplifier having sound entrance and exit openings at its ends, a frame located within said amplifier and extending from the entrance to the exit ends of said amplifier, filamentous resonating elements on said frame and extending transversely of the path of the sound waves passing through said amplifier.

6. A resonator for a sound amplifier comprising a frame having spaced side members, pins extending through one of said side members and having the ends of the pins projecting from said member, filamentous resonating elements connected to said pins and passing across the opposite faces of said frame, eachelementhaving an end secured to a projecting end of a pin and passing across a face of the frame to and around the frame side member opposite from the side member carrying the pins 'and then passing across the opposite face of the frame 10 and back to said pin for securement of the other end of the element to the other projecting end of said in.

In Witness whereo I hereunto subscribe my name to this specification.

FRANK D. ARNOLD. 

